Winds in the AGN environment: new perspectives from high-resolution X-ray spectroscopy

In recent years, winds were recognized as an important ingredient in the AGN picture. Outflows of photoionized gas, which produce blueshifted absorption features detectable in the X-ray and in the UV band, are present in about 50% of Seyfert 1 galaxies. Combining observations at high spectral resolution with photoionization modeling techniques, the kinetics, and the ionization conditions of the outflowing gas can be diagnosed with high accuracy. In this thesis, we applied these methods to three cases of study, obtaining a variety of results. In the X-ray spectrum of the Seyfert 1 galaxy 1H 0419-577, we detected the absorption lines from a galactic scale outflow already observed in the UV. In the case of the prototypical type 1 AGN NGC 5548, we discovered a lowly-ionized, patchy wind located in the nuclear region. We show that the emergence of this obscuring wind have drastically changed the spectral appearance of the source in the soft X-ray and in the UV band. Finally, we characterized a photoionized gas outflow in 4C +74.26, which is one of the few radio-loud AGN in which signatures of photoionized gas could be detected.